Review the status of Korean geoid model development since 2000s and future improvement plan

Abstract

Korean geoid models have been continuously developed for more than 20 years. However, the precision of previous models was approximately 8–15 cm according to evaluations based on newly obtained Global Navigation Satellite System (GNSS)/Leveling data because of irregular distribution and low precision of the gravity and GNSS/Leveling data. Therefore, in 2008, NGII began to obtain new terrestrial gravity and GNSS/Leveling data and collected more than 12,000 points of gravity data and 4492 points of GNSS/Leveling data by the end of 2017. As a result, the newest model, Korean National Geoid 2018 (KNGeoid18), achieved a degree of fit (DOF) of 2.3 cm. The precision was significantly improved compared to previous models including KNGeoid14, but precision in the mountainous areas remained still lower than that of the plain areas. Also, inconsistent differences between the GNSS/Leveling data and KNGeoid18 remained as a problem that should be solved. Through KNGeoid project, the NGII observed a positive effect of supplementing fundamental data, so NGII is obtaining new terrestrial gravity data. Regarding GNSS/Leveling data, the installation of 3D control points was completed in 2019 and the adjustment of GNSS and leveling data is ongoing to allow for the application of verified and adjusted GNSS/Leveling data in the future. Therefore, a new geoid model will be developed until the end of 2023 by applying new terrestrial gravity and GNSS/Leveling data. Overall, it is expected that the precision will be improved to approximately 1–1.5 cm, except in the mountainous areas, owing to new data gathering efforts and the maintenance of the fundamental data.